In vitro digestibility - reducing animal use whilst meeting the demand to evaluate alternative proteins

人们越来越意识到食品既要健康又要可持续，转向更多的植物性食品，减少红肉（如牛肉和羊肉），但继续消费白色肉（如鸡肉），鸡蛋和乳制品。因此，在世界许多地方，禽肉是并将继续是饮食的重要组成部分，但其生产目前非常依赖于给鸡喂食大量的小麦、玉米和大豆，后者提供主要的蛋白质来源。显然，这些作物中的每一种都是人类可食用的，因此有一个真实的推动力来尝试和确定所谓的替代来源，特别是蛋白质来源。人们对一系列替代（未充分利用）作物，如班巴拉花生和四棱豆，以及昆虫，细菌和真菌等新蛋白质来源产生了广泛的兴趣。虽然这些正在研究供人类消费，但它们更有可能更容易被接受（特别是在西方国家）作为动物饲料中小麦、玉米和大豆的替代品。在任何这些蛋白质来源可以用来喂养动物（或人类）之前，重要的是要评估它们的营养价值（即它是否含有适量所需的营养素）和任何可能的负面影响。就膳食蛋白质而言，蛋白质来源的质量取决于其氨基酸组成，特别是必需或不可缺少的氨基酸（必须在膳食中提供的氨基酸）及其消化率。消化率是指动物消化食物和提取所需营养的能力。大豆就是一个很好的例子，因为它含有酶抑制剂（称为抗营养因子），在不加工（例如加热）时会降低其消化率，这意味着动物无法提取大部分营养物质，因此产生更多废物，以粪便和温室气体的形式。因此，消化率差会对环境产生影响，但也会产生商业影响，使食品生产效率低下。在某些情况下，它还可能导致对健康的负面影响，因为无法充分生长或损害消化系统。历史上，食物消化率的测定是使用动物，如家禽、牛、猪或啮齿动物（作为人类的模型）进行的。因此，评估新的食物需要大量的动物，有些食物可能导致消化率降低（因此生长不良），甚至导致健康问题。本项目将比较两种体外（即试管）消化模型，以评估其确定消化率的能力和对抗营养因子存在的敏感性，然后与鸡体内消化率进行比较。总体目标是开发一种准确、灵敏和稳健的体外蛋白质消化方法，用于在动物中进行任何评价之前筛选新的蛋白质来源。这将部分取代和减少未来使用的动物数量，并减少对这些动物的负面影响。

There is increasing awareness of the need for foods to be both healthy and sustainable, with a shift toward more plant-based foods, with reductions in red meat (e.g. beef and lamb) but continued consumption of white meat (e.g. chicken), eggs and dairy products. Hence poultry meat is and will remain an important part of the diet in many parts of the world, but its production is currently very dependent upon feeding chickens significant volumes of wheat, maize and soya, with the latter providing the main protein source. Clearly each of these crops are human edible, so there is a real push to try and identify so-called alternative sources, particularly protein sources. There is wide interest in a range of alternative (under-utilised) crops, such as bambara groundnut and winged bean, as well as novel protein sources such as insects, bacteria and fungi. Although these are being investigated for human consumption, it is more likely that they will be more readily accepted (particularly in western countries) as alternatives to wheat, maize and soya in animal feeds. Before any of these protein sources can be used to feed animals (or humans for that matter), it is important to evaluate both their nutritional value (i.e. does it contain the nutrients required in the right amounts) and any possible negative impacts. In terms of dietary protein, the quality of a protein source is determined by its amino acid composition, particularly the essential or indispensible amino acids (those that must be provided in the diet), as well as their digestibility. Digestibility relates to the ability of an animal to digest its food and extract all the nutrients it needs. Soya is a good example because it contains enzyme inhibitors (called anti-nutritional factors) that reduce its digestibility when it is not processed (e.g. heating), meaning that animals are unable to extract a large proportion of the nutrients present and therefore produce more waste, in the form of faeces and greenhouse gases. Hence, poor digestibility can have environmental impacts, but it also has commercial implications, making food production inefficient. It can, in some cases, also lead to negative impacts on health, due to failure to grow adequately or damage to the digestive system. Historically the determination of digestibility of foods has been done using animals, such as poultry, cattle, pigs or rodents (as models for humans). To evaluate novel foods therefore requires large numbers of animals, with the possibility that some foods might lead to reduced digestibility (and therefore poor growth) or even result in health problems. This project will compare two in vitro (i.e. test-tube) models of digestion, to evaluate their ability to determine digestibility and sensitivity to the presence of anti-nutritional factors, before comparing to in vivo digestibility determined in chickens. The overall aim is to develop an accurate, sensitive and robust in vitro protein digestion method with which to screen novel protein sources prior to any evaluation in animals. This should then partially replace and reduce the numbers of animals being used in the future, as well as reducing the incidence of negative impacts on those animals.